The existing cellular wireless communication system, as shown in FIG. 1, is mainly composed of a Core Network (CN), a Radio Access Network (RAN) and a terminal. The CN is responsible for non-access stratum events, for example terminal position update or the like. The CN is an anchor point of a user plane. The RAN includes a base station, or includes a base station and a base station controller, and is responsible for access stratum events, for example radio resource management. The base stations may be connected physically or logically according to the actual situations, for example the connection between base station 1 and base station 2, or the connection between the base station 1 and base station 3, and each base station may be connected with one or more CN nodes. The terminal, i.e., User Equipment (UE), refers to any device which may be communicated with a cellular wireless communication network, such as a mobile phone or a laptop.
A mobility management unit refers to a Mobility Management Entity (MME) in a Long Term Evolution (LTE) network, or refers to a Serving General Packet Radio Service (GPRS) Support Node (SGSN) in a 3rd Generation (3G) mobile communication network. The MME or the SGSN is a unit responsible for managing terminal access control, location information update and switching in the CN, and responsible for non-access stratum signalling control from the CN to a terminal, as well as has the function of registering the terminal with the network.
Home Subscriber Server (HSS) or Home Location Register (HLR) is an entity in the CN, which is responsible for saving subscription data, identity information, authentication information, authorization information or the like of a terminal. According to different situations, the HSS or the HLR may be configured to save the identity information of a user and the binding information of the user and a terminal device, or only save the identity information of the user (the binding information of the user and the terminal device may be saved by a gateway), or directly save the identity information of the terminal device. The HSS or HLR is also responsible for a subscription database of the user, and performs authentication and authorization for the user. A service platform may make a query to the HSS or the HLR to get user information or terminal information.
In the early time of deployment of LTE, it is impossible to replace all the original 3G networks, which may result in a terminal moving to and fro between the LTE network and the 3G network, thereby resulting in repeated Tracking Area Update (TAU) or Routing Area Update (RAU). The TAU is performed when the terminal moves to the LTE network, and the RAU is performed when the terminal moves to the 3G network. This will cause great signalling consumption. Therefore, an LTE terminal needs to avoid a large number of signalling interactions with the network in an idle state through an Idle state Signalling Reduction (ISR) mode. In the ISR mode, the terminal is registered with the MME and the SGSN simultaneously, in this way, the terminal does not need to perform TAU or RAU when moving between the LTE network and the 3G network (that is, moving between the MME and the SGSN). When data arrives at a Serving Gateway (SGW), the SGW needs to transmit downlink data notification messages to both the MME and the SGSN, so that both of the MME and the SGSN need to transmit paging messages to the terminal.
In a practical application, some terminals do not need to communicate with the network from time to time, for example a location reporting terminal on an express vehicle which reports the current location of the vehicle only when arriving at a certain specified place or according to a specified cycle. Therefore, this type of terminal may use a power saving mode, and set sleep time in the power saving mode. The terminal does not receive any paging message or communicate with the network within the sleep time in the power saving mode, and receives and transmits the data only at the activation time. When entering the power saving mode, the terminal may not receive the paging message, but the network will transmit a paging message when downlink data arrives; at this time, not only the terminal is unable to receive the paging message, but also unnecessary resource waste is caused by repeated paging from the network.